Rotary machines

ABSTRACT

A rotary machine comprising at least one row of rotor blades circumferentially distributed on a rotor and disposed in a rotor blade passage between at least one row of upstream stator blades and at least one row of downstream rotor blades is provided with partitions in the upstream and downstream stator blades to provide a plurality of arcuate segmented flowpaths through the rotor blading. A confined flowpath between a machine inlet and a machine outlet intersects the rotor blading at each arcuate segmented flowpath in turn from the upstream side to the downstream side. This invention when applied to a compressor provides a machine in which several stages of compression of a fluid may be achieved using a single row of rotor blades.

Q United States Patent 1191 1111 3,869,220

Tayler- 1 Mar. 4, 1975 [54] ROTARY MACHINES 1,137,590 4/1915 Ehrhart415/56 3,070,349 12 1962 St t l 5 5 Inventor: g gg i Tayler Bnstol,3,292,899 12/1966 n [73] Assignee: The Secretary of State for Defence inP i E i -C, J, Husar Her Bl'li M testy S Attorney, Agent, orFirmCameron, Kerkam, Sutton. Government of the United Kingdom St &Stowell of Great Britain and Northern Ireland, London, England 57 [22]Filed: Feb. 23, 1973 1 ABSTRACT A rotary machine comprising at least onerow of rotor [2]] Appl- 3351162 blades circumferentially distributed ona rotor and disposed in a rotor blade passage between at least one [30]Foreign Application priority Data row of upstream stator blades and atleast one row of Feb. 23, 1972 Great Britain IIIIIIIIIIIIIII H 8278/72downstream rotor blades is provided with partitions in Jan. 5, 1973Great Britain ..'726/73 the upstream and downstream stator blades toprovide a pluralityof arcuate segmented flowpaths through the 52 us. c1.41s 56 l bladmg' A P f between a machine isli 1m. (:1. F01d 1/12 and amachme (met ntersects the blading 58 Field 61 Search 415/5256 at eacharcuate Segmented flOWPah in mm mm the upstream side to the downstreamside. This invention [56] References Cited when applied to a compressorprovides a machine in which several stages of compression of a fluid maybe 1 099 970 D ZZI PATENTS 415/56 achieved using a single row of rotorblades.

o 1,118,557 11/1914 Kubiak 415/56 10 Claims, 6 Drawing Figures c 4 8 9fl "J htu'"*"' .20 I I llama 26 27 IIIA'IIIIIAMII PATENTEU 41975 3, 86922 0 sum 1 95 5 ROTARY MACHINES This invention relates to rotarymachines, more particularly to compressors requiring a high pressureratio and/or low mass flows for refrigeration and cryogenic pumping.

In cryogenies, pneumatics for instrumentation or control, andrefrigeration, in which high pressure ratios and very low flows arerequired, pumping is usually carried out by a reciprocating compressor;however, because of its size, weight, and the problem of oilcontamination, other solutions to the pumping problem have been sought.

Thus more recently a multistage centrifugal compressor for cryogenicduties in the production of liquid helium has been developed. Because ofthe low flows involved, the size of each unit is very small and a veryhigh rotational speed (up to 200,000 rpm) is required. No suitable primemover for industrial use is widely available, and such prime movers haveproved difficult to develop.

It is therefore an object of the present invention to provide a machinefor coping with low flows and/or high pressure ratios of compact sizeand capable of being driven by commonly available prime movers.

A subsidiary object is to provide a machine for coping with low flowsand/or high pressure ratios in which oil contamination is avoided.

A compressor constructed in accordance with the present invention takesadvantage of the high efficiency and pressure rise obtainable with asingle stage axial machine, regenerating this a controlled number oftimes. To obtain the same pressure rise with low flows with conventionalmultistage axial flow compressors, would theoretically require suchsmall blades in the later stages as to be virtually microscopic.

It has been found that a compressor according to the present inventiondesigned for the same cryogenic duties as the known centrifugalcompressor requires a rotational velocity of less than a quarter of thatof the centrifugal compressor.

In order that the invention might be more fully understood and furtherfeatures appreciated the following description will refer to theaccompanying drawings, in which:

FIG. I is an axial view of a first compressor according to the inventionadapted to operate upon compressible fluid sectioned on the line CC ofFIG. 2.

FIG. 2 is a section on the line EE of FIG. 1,

FIG. 3 is a developed view of the confined flowpath of the compressor ofFIG. 1,

FIG. 4 is a longitudinal section of a second compressor according to theinvention sectioned on the line ZZ of FIG. 6,

FIG. 5 is a transverse section of the second compressor sectioned on theline XX of FIG. 4, and

FIG. 6 is a further transverse section of the second compressorsectioned on the line YY of FIG. 4.

In FIGS. 1' to 3 the illustrated compressor comprises a rotor I mountedon a shaft 2 provided with a flange for connection to a prime mover (notshown). The shaft 2 is journalled at bearing 11 into the case 8; bearing11 would be a gas bearing particularly when it is desired to eliminatethe risk of oil contamination. A plurality of radially directed aerofoilsectioned rotor blades 3 are circumferentially distributed around theperiphery of rotor 1 and operate in a space 4, known as the rotor bladepassage, between a row of upstream stator blades 5 and a row ofdownstream stator blades 6, both of the rows of stator blades beingcircumferentially disposed in an annular aperture 44 around rotor 1. Therows of stator blades 5 and 6 extend from the inner surface of anannulus 7 disposed outside the blade tips of the row of rotor blades 3.A toroidal space 9 outside annulus 7 is formed between the case 8 andannulus 7, into which toroidal space 9 the annular aperture 44 aroundthe rotor opens at both ends.

The annular aperture 44 the rotor 1 intersecting the row of rotor blades3 is divided by a plurality of radially directed circumferentiallydistributed partitions 12 (in upstream stator blade row 5) and 24 (indownstream blade row 6) the partitions 12 and 24 each occupying at leastone stator blade pitch. The partitions 24 are slightly displaced in thedirection of rotation of the rotor the partitions 12 (the arrangementbeing most clearly shown in FIG. 3). The partitions 12 and 24 divide theannular aperture around rotor 1 into a plurality of successivelyarranged arcuate segmented flowpaths 13-19 each intersecting a portionof the rotor blade row. As the illustrated compressor is specificallyadapted for compressing a compressible fluid (e.g. helium gas), thearcuate segmented flowpaths are of decreasing aperture from the first,13, to the last, 19. Entry to the first arcuate segmented flowpath 13 isprovided by a convergent inlet channel 20 extending outside case 8, andwhose wall 21 terminates at a flange 22 to which a low pressure fluidsource may be connected. Each partition 24 extends from the stator bladerow 6 into the toroidal space 9 and is continued to join the nextfollowing partition 12 which is similarly extended from the stator bladerow 5 into the toroidal space 9, the extended partitions 12 and 24occupy the whole height between the case 8 and annulus 7 therebydefining a plurality of return flowpaths 32 to 37 within the casing 8angled to the axis of the shaft 2, each leading from downstream of onearcuate segmented flowpath to upstream of the next following arcuatesegmented flowpath; thus return flowpath 32 leads from the downstreamside of arcuate segmented flowpath 13 to the upstream side of the nextfollowing arcuate segmented flowpath l4, and return flowpath 33 leadsfrom the downstream side of arcuate segmented flowpath 14 to theupstream side of arcuate segmented flowpath 15 around the rotor bladetips. Downstream of the last arcuate segmented flowpath 19 a divergentdiffuser passage extends through case 8 forming an outlet 25 whose walls26 have a flange 27 for connection to a high pressure fluid sink (notshown). It will be seen that the com bination of arcuate segmentedflowpaths and return flowpaths 13, 32,14, 33, 15, 34,16, 35, 17, 36, 18,37, I9, taken in turn provides a confined flowpath from inlet 20 tooutlet 25 intersecting the row of rotor blades seven times.

Conveniently the annulus 7 is flared outwards toward its edges 38 and 39so that feed back channels 32 37 take a convergent form on theirapproach to the arcu' ate segmented flowpaths 14 19 and a divergentdiffuser form 23 downstream of segmented flowpaths 13 In use the row ofrotor blades 3 is normally driven from intersection with a lowerpressure arcuate segmented flowpath to intersection with a higherpressure arcuate segmented flowpath, eg from arcuate flowpath 16 toarcuate segmented flowpath 17. To prevent high losses due to compressedfluid being passed from the high pressure final stage of compression inarcuate segmented flowpath 19 back to the low pressure first stage ofcompression in arcuate flowpath 13, the partition particularlydesignated 42 in the upstream row of stator blades 5 between arcuatesegmented flowpath l9 and arcuate segmented flowpath 13 is considerablythicker than the other partitions l2 and 24.

Rotor 1 and rotor blades 3 are formed from a single disc forging withthe row of rotor blades 3 being machined to an aerofoil sectionintegrally from the forged disc. To prevent leakage along the face ofthe rotor, seals 28 are provided between the face of the rotor and afixed annular hub 29 which has a central orifice 30 through which shaft2 passes and a circumferential flange 31 forming part of the wall offeedback flowpaths 32 37.

A lateral frusto-conical hub 40 fitted to an internal flange 41 of case8 covers the remaining exposed portion of rotor 1.

Flow of compressible fluid, for which this particular compressor isadapted, can most easily be followed by reference to FIG. 3.

Compressible fluid (e.g. helium gas) from low pressure source enters themachine through convergent entry inlet and passes through arcuatesegmented flowpath l3 intersecting parts of the rows of stator blades 5,rotor blades 3, and stator blades 6 in turn, so entering the diffuser 23forming part of feedback flowpath 32, the flow returns around theoutside of annulus 7 before entering the following arcuate segmentedflowpath 14 to intersect the row of rotor blades again. This process isrepeated on five further occasions until the flow passes through thelast arcuate segmented flowpath l9 and leaves the machine through outlet25, having intersected the row of rotor blades on seven occasions.

The isothermal efficiency of the machine can be improved by providingintercooling between stages of compression. This is most easily arrangedby providing that the feedback flowpaths are formed in ducts around theoutside of the case as illustrated in FIGS. 4 to 6.

ln FIGS. 4 to 6 those items common to FIGS. 1 to 3 are given the samereference numerals. The compressor of FIGS. 4 to 6 comprises a rotor Imounted on a shaft 2 journalled into case 8 at one end and lateral hub45 bolted to the case 8 at the other. A row of radially directedaerofoil sectioned rotor blades 3 are circumferentially distributedaround the rotor 1 and operate in a space 4, the rotor blade passage,between a row of upstream stator blades 5 and a row of downstream statorblades 6, both of said rows of stator blades comprising a plurality ofradially directed blades disposed in an annular aperture 44 around theperiphery of rotor 1. The blades of rows of stator blades 5 and 6 occupythe full height of annular aperture 44.

Aperture 44 is divided by radially directed partitions 24 in the row ofstator blades 6 not less than one rotor blade pitch in width, andsimilar opposed partitions (not shown) in the row ofstator blades 5.These partitions provided a plurality of discreet arcuate segmentedflowpaths through the row of rotor blades 3; in the compressorillustrated there are four arcuate segmented flowpaths l3 16. As thiscompressor is adapted to compress a compressible fluid, eg helium gas,the arcuate segmented flowpaths are of decreasing aperture from thefirst 13 to the last 16.

A convergent passage passes through the lateral hub 45 and forms aninlet 20 to the first arcuate segmented pass 13. The wall 21 of inlet 20is provided with a flange at its outer end which may be used to connectthe compressor to a low pressure source of compressible fluid. At itsinner end the wall 21 is formed integrally with the partitions in therow of stator blades 5 defining the arcuate segmented flowpath l3.

Downstream of arcuate segmented flowpath 13 is provided a feedbackflowpath 46 around the outside of the rotor to the next arcuatesegmented flowpath 14 through a further portion of the row of rotorblades 3. Subsequent feedback flowpaths 47, 48 from downstream ofarcuate segmented flowpath 14 to upstream of arcuate segmented flowpathl5, and from downstream of arcuate segmented flowpath 15 to upstream ofarcuate segmented flowpath 16 provide a confined flowpath from the inlet20 to an outlet 25 downstream of arcuate segmented flowpath 16. The wall26 of outlet 25 has a flange 27 which may be connected to a highpressure sink for the compressed fluid.

Feedback flowpaths 46, 47, 48 each comprise a confined path through adivergent diffuser 23, and offset 180 bend 49, return duct 50, offset180 bend 51, and convergent channel 52 from the downstream side of onearcuate flowpath to the upstream side of the next following arcuateflowpath. The side walls of the divergent diffusers 23 are integrallyfromed with the partitions 24. Divergent diffusers 23 are each connectedthrough an offset l bends 49 to a return duct 50 around the outside ofrotor 1. The return duct 50 is provided with intercooling comprising, inthis instance. a honeycomb of piping 53 through which coolant fluid maypass between an inlet 54 and outlet 55. The flowpath on leaving returnduct 50 enters another offset bend 51 to a convergent passage 52 on theupstream side of the next following arcuate segmented flowpath throughthe row of rotor blades 3.

The provision of intercooling in the return ducts 50 greatly improvesthe isothermal efficiency of machines of this type.

When the machine is to be used in compressing compressible fluids, suchas helium gas, the arcuate segmented flowpaths through the row of rotorblades are of decreasing aperture from the first 13, to the last 16'.furthermore the cross-sectional areas of equivalent parts of thefeedback flowpaths 46, 47, 48 also decrease from the first 46 to thelast 48.

The rotor blades 3 are normally driven from a lower pressure arcuatesegmented flowpath to a higher pressure arcuate segmented flowpath, thatis in such a direction as to drive any fluid carried over in the rotorblades from a lower pressure to a higher pressure, eg from arcuatesegmented flowpath 14 to arcuate segmented flowpath 15.

In this embodiment the partitions are several stator blade pitches inthickness, and leakage between passes is minimised.

Rotor 1 and its blades 3 are formed from a single disc forging, thebaldes 3 being machined to an aerofoil section integrally from theforged disc. In order to prevent leakage from the blade tips and betweenarcuate flowpaths, the row of rotor blades 3 are manufactured to haveclose tolerance with the rows of stator blades 5 and 6. Furthermore toprevent leakage along the face of the rotor, seals 28 are providedbetween both faces of the rotor and the body of the machine.

In operation, compressible fluid from a low pressure source enters thecompressor through convergent entry channel 20 to arcuate segmentedflowpath 13 through a portion of the tow of rotor blades 3. The inletflow makes its first pass through a portion of the upstream row ofstator blades 5 separated from flows in the adjoining arcuate segmentedflowpaths 14 and 16 by the partitions. After passing through theupstream stator blades where the flow is directed towards the rotatingrotor blades at the required angle, energy is imparted to the fluid.Some of the energy is converted to pressure rise in the diffusing rotorblade passages, and some in the following stationary row of downstreamstator blades 6. Further conversion of fluid velocity to pressure riseis carried out in the following diffuser 23 forming part of feedbackflowpath 46. The fluid then turns through 180 in bend 49.

The fluid passes back through duct 50 making contact with the coolingsurface on intercooling piping 53 before executing another 180 turn inbend 51 from which convergent channel 52 takes the fluid into the statorblades in arcuate segmented flowpath 14. The fluid on leaving arcuatesegmented flowpath 14 repeats the process in feedback flowpath 47. Thefluid flowpath is therefore of a controlled pattern, the width of eachsuccessive arcuate flowpath being designed to match the reduced arearequired for the increase in fluid density. The fluid passes througheach of the arcuate segmented flowpaths 13, 14, 15, 16 in turn beingdirected from the downstream side of one arcuate segmented flowpath tothe upstream side of the next feedback flowpaths 46, 47, 48 in turn. Thefluid leaves the last arcuate segmented flowpath l6 and enters thediffusing outlet 25 by which it leaves the compressor at a highpressure, having passed through portions of the row of rotor blades fourtimes.

The invention has been particularly described in its simplest form withthe rotor having blades 21 single row of rotor blades and one row eachof upstream and downstream stator blades. The invention is not limitedto this configuration, for the rotor may have a plurality of rows ofrotor blades operating between a plurality of rows of stator blades, sothat when fluid passes through a arcuate flowpath it undergoesmultistage compression before being fed back to the next followingarcuate segmented flowpath.

Furthermore the described method of intercooling in FIGS. 4 to 6 with ahoneycomb of longitudinal water cooling pipes along the return duct isintended as merely being illustrative of the intercooling. Many methodsof providing intercooling will occur to those versed in the art and anysuch method could be used in the present invention.

It may be found advantageous in the compressor of F108. 4 to 6 toreplace the 180 offset right angle bends by plenum chambers.

The partitions in this second embodiment are considerably thicker (atleast three stator blade pitches) than those illustrated in the firstembodiment in FIGS. 1 to 3. Thus in this second embodiment there is noparticular need to construct the partition between the last and thefirst arcuate flowpath more thickly than the others.

The number of arcuate flowpaths provided around the rotor is a matter ofdesign, the embodiments described with reference to the figures aremerely illustrative in showing seven and four arcuate flowpathsrespectively, any convenient number of such arcuate flowpaths may beprovided to suit the particular application for the machine.

Again the illustrated embodiments were of machines adapted for use withcompressible fluids, however where the fluid to be operated on isincompressible the arcuate flowpaths would be of equal aperture.

It is not necessary for the direction of rotation of the rotor to be asdescribed, this invention would not preclude the rotation of the rotorgenerally from a high pressure environment to a lower pressureenvironment, stepping, of course, back to a high pressure environmentbetween the first and the last arcuate segmented pass.

1 claim:

1. A compressor comprising a case and mounted within said case:

a. a rotor,

b. an annular aperture coaxial with said rotor and surrounding theperiphery of said rotor,

c. at least one row of rotor blades circumferentially distributed on theperiphery of the rotor and projecting into said annular aperturedividing the annular aperture into an upstream side and a downstreamside,

d. a row of upstream stator blades radially directed andcircumferentially distributed around the interior of said annularaperture, occupying the whole height of said annular aperture anddisposed upstream of said row of rotor blades,

e. a row of downstream stator blades radially directed andcircumferentially distributed around the interior of said annularaperture, occupying the whole height of said annular aperture, anddisposed downstream of said row of rotor blades,

. a rotor blade passage formed between said row of upstream statorblades and said row of downstream rotor blades wherein said row of rotorblades operates,

g. partitions provided in each row of stator blades, each partitionoccupying at least one stator blade pitch, each partition in thedownstream row of stator blades being substantially opposed by acorresponding partition in the upstream row of stator blades,

h. a plurality of arcuate segmented flowpaths arranged around theperiphery of the rotor intersecting said row of rotor blades in adirection substantially normal to the direction of travel of the rotorblades, each of said arcuate segmented flowpaths being formed betweenpairs of corresponding partitions in said upstream and said downstreamrows of stator blades, the arcuate segmented flowpaths being arrangedsuccessively from a first arcuate segmented flowpath to a last arcuatesegmented flowpath,

. a plurality of confined return flowpaths, each of said returnflowpaths being associated with an arcuate segmented flowpath except thelast arcuate segmented flowpath, wherein each of the return flowpathsruns from the downstream side of its associated arcuate segmentedflowpath to the upstream side of the next following arcuate seg mentedflowpath,

j. an inlet from without the case to the first arcuate segmentedflowpath, and

k. an outlet from the last arcuate segmented flowpath to without thecase.

2. A compressor according to claim 1 additionally including: an annulusaround said annular aperture and coaxial with the rotor, a toroidalchamber provided within the case, and said plurality of return flowpathsbeing within said toroidal chamber.

3. A compressor according to claim 2 wherein said confined returnflowpaths each comprises an enclosed pipe from downstream of itsassociated arcuate segmented flowpath to upstream of the next followingsegmented flowpath.

4. A compressor according to claim 3 including two 180 off-set bends ineach of said enclosed pipes.

5. A compressor according to claim 3 including two plenum chambers ineach of said enclosed pipes.

6. A compressor according to claim 3 including a convergent passageimmediately upstream of each arcuate segmented flowpath and a divergentpassage immediately downstream of each arcuate segmented flowpath.

7. A compressor according to claim 2 including extensions of saidpartitions into said toroidal chamber each extension occupying the wholeheight of said toroidal chamber and wherein the extension of a partitionin the row of downstream stator blades is integrally formed with theextension of the next following partition from its corresponding opposedpartition in the row of upstream stator blades, and said confined returnflowpath formed between the integrally formed partition extensions.

8. A compressor according to claim 7 additionally comprising a thickerpartition between the last arcuate segmented flowpath and the firstarcuate segmented flowpath in the upstream row of stator blades than theother partitions.

9. A compressor comprising a case and mounted within said case:

a. a rotor,

b. an annular aperture coaxial with said rotor and surrounding theperiphery of said rotor,

c. at least one row of rotor blades circumferentially distributed on theperiphery of the rotor and projecting into said annular aperturedividing the annular aperture into an upstream side and a downstreamside,

d. at least one row of upstream stator blades radially directed andcircumferentially distributed around the interior of said annularaperture, occupying the whole height of said annular aperture, anddisposed upstream of said row of rotor blades,

e. at least one row of downstream stator blades radially distributedaround the interior of said annular aperture, occupying the height ofsaid annular aperture, and disposed downstream of said row of rotorblades,

f. a rotor blade passage formed between said row of upstream statorblades and said row of downstream stator blades wherein said row ofrotor blades operates,

g. partitions provided in each row of stator blades, each partitionoccupying at least one stator blade pitch, each partition in thedownstream row of stator blades being substantially opposed by acorresponding partition in the upstream row of stator blades.

h. a plurality of arcuate segmented flowpaths arranged around theperiphery of the rotor intersecting said row of rotor blades in adirection substantially normal to the direction of travel of the rotorblades, each of said arcuate segmented flowpaths being formed betweenpairs of corresponding partitions in said upstream and said downstreamrows of stator blades, the arcuate segmented flowpaths being arrangedsuccessively from a first arcuate segmented flowpath to a last arcuatesegmented flowpath,

. a plurality of confined return flowpaths, each of said returnflowpaths being associated with an arcuate segmented flowpath except thelast arcuate segmented flowpath, wherein each of the return flow pathsruns from the downstream side of its associated arcuate segmentedflowpath to the upstream side of the next following arcuate segmentedflowpath,

j. an inlet from without the case to the first arcuate segmentedflowpath,

R. an outlet from the last arcuate segmented flowpath to without thecase,

1. an annulus around said annular aperture and coaxial with the rotor,

m. a toroidal chamber provided within the case, and said plurality ofreturn flowpaths being within said toroidal chamber, n. said confinedreturn flowpaths each comprising an enclosed pipe from downstream of itsassociated arcuate segmented flowpath to upstream of the next followingsegmented flowpath,

0. two off-set bends in each of said enclosed pipes,

p. a convergent passage immediately upstream of each arcuate segmentedflowpath and a divergent passage immediately downstream of each arcuatesegmented flowpath.

10. A compressor comprising a case and mounted within said case:

a. a rotor,

b. an annular aperture coaxial with said rotor and surrounding theperiphery of said rotor,

c. at least one row of rotor blades circumferentially distributed on theperiphery of the rotor and projecting into said annular aperturedividing the annular aperture into an upstream side and a downstreamside,

d. at least one row of upstream stator blades radially directed andcircumferentially distributed around the interior of said annularaperture, occupying the whole height of said annular aperture, anddisposed upstream of said row of rotor blades,

e. at least one row of downstream stator blades radially distributedaround the interior of said annular aperture, occupying the whole heightof said annular aperture, and disposed downstream of said row of rotorblades,

f. a rotor blade passage formed between said row of upstream statorblades and said row of downstream stator blades wherein said row ofrotor blades operates,

g. partitions provided in each row of stator blades, each partitionoccupying at least one stator blade pitch, each partition in thedownstream row of stator blades being substantially opposed by acorresponding partition in the upstream row of stator blades,

h. a plurality of arcuate segmented flowpaths arranged around theperiphery of the rotor intersecta plurality of confined returnflowpaths, each of said return flowpaths being associated with anarcuate segmented flowpath except the last arcuate segmented flowpath,wherein each of the return flowpaths runs from the downstream side ofits associated arcuate segmented flowpath t the upstream side of thenext following arcuate segmented flowpath,

an inlet from without the case to the first arcuate segmented flowpath,

k, an outlet from the last arcuate segmented fiowpath to without thecase,

1. an annulus around said annular aperture and coaxial with the rotor,

m. a toroidal chamber provided within the case. and

said plurality of return flowpaths being within said toroidal chamber,

n. extensions of said partitions into said toroidal chamber eachextension occupying the whole height of said toroidal chamber andwherein the extension ofa partition in the row of downstream statorblades is integrally formed with the extension of the next followingpartition from its corresponding opposed partition in the row ofupstream stator blades, and said confined return fiowpath formed betweenthe integrally formed partition extension, 0. a thicker partitionbetween the last arcuate segmented flowpath and the first arcuatesegmented flowpath in the upstream row of stator blades wider

1. A compressor comprising a case and mounted within said case: a. arotor, b. an annular aperture coaxial with said rotor and surroundingthe periphery of said rotor, c. at least one row of rotor bladescircumferentially distributed on the periphery of the rotor andprojecting into said annular aperture dividing the annular aperture intoan upstream side and a downstream side, d. a row of upstream statorblades radially directed and circumferentially distributed around theinterior of said annular aperture, occupying the whole height of saidannular aperture and disposed upstream of said row of rotor blades, e. arow of downstream stator blades radially directed and circumferentiallydistributed around the interior of said annular aperture, occupying thewhole height of said annular aPerture, and disposed downstream of saidrow of rotor blades, f. a rotor blade passage formed between said row ofupstream stator blades and said row of downstream rotor blades whereinsaid row of rotor blades operates, g. partitions provided in each row ofstator blades, each partition occupying at least one stator blade pitch,each partition in the downstream row of stator blades beingsubstantially opposed by a corresponding partition in the upstream rowof stator blades, h. a plurality of arcuate segmented flowpaths arrangedaround the periphery of the rotor intersecting said row of rotor bladesin a direction substantially normal to the direction of travel of therotor blades, each of said arcuate segmented flowpaths being formedbetween pairs of corresponding partitions in said upstream and saiddownstream rows of stator blades, the arcuate segmented flowpaths beingarranged successively from a first arcuate segmented flowpath to a lastarcuate segmented flowpath, i. a plurality of confined return flowpaths,each of said return flowpaths being associated with an arcuate segmentedflowpath except the last arcuate segmented flowpath, wherein each of thereturn flowpaths runs from the downstream side of its associated arcuatesegmented flowpath to the upstream side of the next following arcuatesegmented flowpath, j. an inlet from without the case to the firstarcuate segmented flowpath, and k. an outlet from the last arcuatesegmented flowpath to without the case.
 2. A compressor according toclaim 1 additionally including: an annulus around said annular apertureand coaxial with the rotor, a toroidal chamber provided within the case,and said plurality of return flowpaths being within said toroidalchamber.
 3. A compressor according to claim 2 wherein said confinedreturn flowpaths each comprises an enclosed pipe from downstream of itsassociated arcuate segmented flowpath to upstream of the next followingsegmented flowpath.
 4. A compressor according to claim 3 including two180* off-set bends in each of said enclosed pipes.
 5. A compressoraccording to claim 3 including two plenum chambers in each of saidenclosed pipes.
 6. A compressor according to claim 3 including aconvergent passage immediately upstream of each arcuate segmentedflowpath and a divergent passage immediately downstream of each arcuatesegmented flowpath.
 7. A compressor according to claim 2 includingextensions of said partitions into said toroidal chamber each extensionoccupying the whole height of said toroidal chamber and wherein theextension of a partition in the row of downstream stator blades isintegrally formed with the extension of the next following partitionfrom its corresponding opposed partition in the row of upstream statorblades, and said confined return flowpath formed between the integrallyformed partition extensions.
 8. A compressor according to claim 7additionally comprising a thicker partition between the last arcuatesegmented flowpath and the first arcuate segmented flowpath in theupstream row of stator blades than the other partitions.
 9. A compressorcomprising a case and mounted within said case: a. a rotor, b. anannular aperture coaxial with said rotor and surrounding the peripheryof said rotor, c. at least one row of rotor blades circumferentiallydistributed on the periphery of the rotor and projecting into saidannular aperture dividing the annular aperture into an upstream side anda downstream side, d. at least one row of upstream stator bladesradially directed and circumferentially distributed around the interiorof said annular aperture, occupying the whole height of said annularaperture, and disposed upstream of said row of rotor blades, e. at leastone row of downstream stator blades radially distributed around theinterior of said annular aperture, occupying the height of said annularaperture, and disposed downstream of said row of rotor blades, f. arotor bLade passage formed between said row of upstream stator bladesand said row of downstream stator blades wherein said row of rotorblades operates, g. partitions provided in each row of stator blades,each partition occupying at least one stator blade pitch, each partitionin the downstream row of stator blades being substantially opposed by acorresponding partition in the upstream row of stator blades. h. aplurality of arcuate segmented flowpaths arranged around the peripheryof the rotor intersecting said row of rotor blades in a directionsubstantially normal to the direction of travel of the rotor blades,each of said arcuate segmented flowpaths being formed between pairs ofcorresponding partitions in said upstream and said downstream rows ofstator blades, the arcuate segmented flowpaths being arrangedsuccessively from a first arcuate segmented flowpath to a last arcuatesegmented flowpath, i. a plurality of confined return flowpaths, each ofsaid return flowpaths being associated with an arcuate segmentedflowpath except the last arcuate segmented flowpath, wherein each of thereturn flow paths runs from the downstream side of its associatedarcuate segmented flowpath to the upstream side of the next followingarcuate segmented flowpath, j. an inlet from without the case to thefirst arcuate segmented flowpath, k. an outlet from the last arcuatesegmented flowpath to without the case, l. an annulus around saidannular aperture and coaxial with the rotor, m. a toroidal chamberprovided within the case, and said plurality of return flowpaths beingwithin said toroidal chamber, n. said confined return flowpaths eachcomprising an enclosed pipe from downstream of its associated arcuatesegmented flowpath to upstream of the next following segmented flowpath,o. two 180* off-set bends in each of said enclosed pipes, p. aconvergent passage immediately upstream of each arcuate segmentedflowpath and a divergent passage immediately downstream of each arcuatesegmented flowpath.
 10. A compressor comprising a case and mountedwithin said case: a. a rotor, b. an annular aperture coaxial with saidrotor and surrounding the periphery of said rotor, c. at least one rowof rotor blades circumferentially distributed on the periphery of therotor and projecting into said annular aperture dividing the annularaperture into an upstream side and a downstream side, d. at least onerow of upstream stator blades radially directed and circumferentiallydistributed around the interior of said annular aperture, occupying thewhole height of said annular aperture, and disposed upstream of said rowof rotor blades, e. at least one row of downstream stator bladesradially distributed around the interior of said annular aperture,occupying the whole height of said annular aperture, and disposeddownstream of said row of rotor blades, f. a rotor blade passage formedbetween said row of upstream stator blades and said row of downstreamstator blades wherein said row of rotor blades operates, g. partitionsprovided in each row of stator blades, each partition occupying at leastone stator blade pitch, each partition in the downstream row of statorblades being substantially opposed by a corresponding partition in theupstream row of stator blades, h. a plurality of arcuate segmentedflowpaths arranged around the periphery of the rotor intersecting saidrow of rotor blades in a direction substantially normal to the directionof travel of the rotor blades, each of said arcuate segmented flowpathsbeing formed between pairs of corresponding partitions in said upstreamand said downstream rows of stator blades, the arcuate segmentedflowpaths being arranged successively from a first arcuate segmentedflowpath to a last arcuate segmented flowpath, i. a plurality ofconfined return flowpaths, each of said return flowpaths beingassociated with an arcuate segmented flowpath except the last arcuatesegmeNted flowpath, wherein each of the return flowpaths runs from thedownstream side of its associated arcuate segmented flowpath to theupstream side of the next following arcuate segmented flowpath, j. aninlet from without the case to the first arcuate segmented flowpath, k.an outlet from the last arcuate segmented flowpath to without the case,l. an annulus around said annular aperture and coaxial with the rotor,m. a toroidal chamber provided within the case, and said plurality ofreturn flowpaths being within said toroidal chamber, n. extensions ofsaid partitions into said toroidal chamber each extension occupying thewhole height of said toroidal chamber and wherein the extension of apartition in the row of downstream stator blades is integrally formedwith the extension of the next following partition from itscorresponding opposed partition in the row of upstream stator blades,and said confined return flowpath formed between the integrally formedpartition extension, o. a thicker partition between the last arcuatesegmented flowpath and the first arcuate segmented flowpath in theupstream row of stator blades wider than the other partitions.